1. Field of the Invention
The present invention relates to an image sensor apparatus with noise cancellation circuitry suitable for use in facsimile equipment, a compact type image reader, or the like.
2. Description of the Related Art
An image sensor apparatus obtains an image signal by converting an optical signal from an original into an electrical signal by means of a large number of linearly arranged optical/electrical conversion elements. In the conventional image sensor apparatus, there has been such a difficulty that various unwanted signals, e.g., a noise signal produced when a switch is operated, cause deterioration in the S/N ratio of the image signal to thereby make it impossible to obtain an image of high quality.
In U.S. Pat. No. 4,600,843, there is disclosed a method to reduce noises in an image sensor. The method disclosed therein, however, is used in an arrangement in which the output signals of optical/electrical conversion elements are serially taken out, and the patent specification does not refer to reduction of noise signals in such an image sensor apparatus in which optical/electrical conversion elements are connected to form a matrix array and its output portion is formed of a plurality of signal lines, for example, of 32 channels, and image signals are taken out in parallel.